Pulping apparatus



Jan. 13, 1970' w. H. COMES ET AL I 3,489,356

PULPING APPARATUS Filed Sept. 20, 1966 W 2 Sheets-Sheet 1 I N VEN TORSWILLIAM H. COMBS SAM N. CRAIG ELLIS R` WARNER, JR.

ATTORNEYS.

Jan. 13, 1970 w. H. COMES ET AL'. 3,489,356

PULPING APPARATUS Filed Sept. 20, 1965 2 Sheets-Sheet 2 4gb B c l l 38 A*a D 30 4o Fv S- /f/ 1 28 36 j E H IC7/Q 5 Fig. 4

Fl'g. 5

JNVENTORS.

I WlLLlAM H. COMBS SAM N. C Al R G ELUS R. WARNER,JR.

BY @M+-M ATTORNEYS.

United States Patent M PULPING APPARATUS William H. Combs, Wayne, Sam N.Craig, Devon, and

Ellis R. Warner, Jr., West Chester, Pa., assxgnors to Wascon Systems,Incorporated, Hatboro, Pa., a corporation of Pennsylvania Filed Sept.20, 1966, Ser. No. 580,445

Int. Cl. B02c 7/08, 7/12, 13/28 U.S. Cl. 241--74 16 Claims ABSTRACT 0FTHE DISCLOSURE A pulping apparatus is provided, comprising a slurry tankhaving an impeller mounted at the bottom thereof, for rotation, wherebycircular movement of the slurry is eiected. Teeth are provided on theimpeller for pulping the slurry solids, and the slurry is discharged fomthe tank by being impelled through a screen. Vanes on the impeller causethe circulating slurry to pulsate to eifectively dislodge solidparticles which may otherwise tend to lodge in or on the screens.

'I'his invention relates generally to pulping apparatus for the solidsin a liquid slurry thereof, and particularly to pulping apparatus of thetype wherein the mixture of liquid and solids to be pulped is containedin a tank which is provided with an impeller mounted in the bottomthereof for rotation on a vertical axis, whereby to cause circulatorymovement o-f the mixture of liquid and solids, and which is alsoprovided with a screen located in the path of the solids discharged bythe impeller and controlling the passage of pulped particles to theoutlet from the tank.

An important object of the invention is to provide pulping apparatus ofthe type aforesaid wherein the impeller has novel and improvedstructural characteristics which give increased insurance againstclogging of the screen.

Another object is to provide such an impeller which effects continuouscleaning of the perforations of the screen by causing the material topulsate, the pulsing action being effective to dislodge particles ofsolids tending to lodge in Oron the screen.

Another object is to provide such an impeller with improved cuttingteeth for reducing the solids in the liquid slurry thereof to a pulp,and for shedding any incompletely pulped solids tending to dwellthereon.

Other objects of the invention will become apparent when the followingdescription is read with reference to the accompanying drawings, inwhich:

FIGURE l is a vertical, longitudinal section through apparatusconstructed in accordance with the invention;

FIGURE 2 is a section on line II-II in FIGURE l;

FIGURE 3 is an enlarged section on line III-III in FIGURE 2;

FIGURE 4 is a perspective view of a block illustrating how the cuttingteeth may be made; and i FIGURE 5 is an enlarged section on line V-V inFIGURE 2, showing one of the cutting teeth, made as indicated in FIGURE4, affixed to the `upper surface of the impeller plate.

The following description is directed to the specific form of theinvention shown in the drawings and is not addressed to the scope of theinvention, which may be practiced in a variety of forms.

Apparatus constructed in accordance with the invention comprises apulping tank provided with a dished bottom 12 which has a large opening14 centrally thereof. Underlying the opening 14 is a closure, generallydesignated 16, including a screen 18 depending from the dished bottom 12and having a plate 20 extending across the lower extremity thereof. Adischarge conduit 22 is Patented Jan. 13, 1970 provided for receivingmaterial discharged from the tank lil through the screen 18 andconducting it to a pump (not shown).

Extending upwardly through the conduit 22 and the plate 20 is a shaft2.4 to the upper extremity of which is aflixed an impeller, generallydesignated 26. The impeller is provided with a main body in the form ofa circular plate 28 disposed centrally within the screen 18.

Mounted upon the upper surface of the plate 28 is a set of four vanesequally spaced circumferentially about the outer marginal area of theplate. Each vane is in the form of an upstanding plate triangular inshape, being provided with long edges 36 and 38 substantially equal inlength and a comparatively short edge 40. The long edge 36 is seatedupon the upper surface of the plate 28 and secured thereto, as bywelding. The vane is disposed with the llong edge 38 leading. Alternateones of the vanes, generally designated 30, are disposed with theirleading ends farther away from the edge of the plate 28 than their`trailing ends, while intervening ones of the vanes, generallydesignated 32, are disposed with their leading ends closer to the edgeof the plate 28 than their trailing ends. In addition to the vanes 38and 32, the outer marginal area of the plate 28 has distributedthereover a multiplicity of cutting teeth, designated 42. Referringparticularly t0 FIGURE 4, a block of metal A, B, C, D, E, F, G, H isshown cut along a diagonal A-G in such a way as to produce two identicalcutting teeth 42a and 42h, each tooth being thus provided with a largediamond-shaped surface A, I, G, I. As illustrated in FIGURE 5, the teethare secured to the upper surface of the plate (as by welding) with thediamond-shaped surface facing downwardly and, typically, the cuttingedge A, E (or C, G) leading. Each said tooth 42, along opposite sides ofits leading edge A, E, for example, has non-parallel apex-dening opposedsurface portions slopped toward each other and which are connected toeach other along the leading edge A, E, said surface portions alsoconnecting the leading edge with the upper surface of the impeller, forat least the length of the leading edge, as is clearly indicated inFIGURES 2, 4, and 5.

In the operation of the apparatus, the tank 10 is charged with a mixtureof water and solids, for example, waste materials, and the impeller isrotated in the direction indicated by the arrow in FIGURE 2. The solidsare cut up into pulp by the cutting action of teeth 42. The vanes areoperative to move the materials circumferentially, and as the solids arecut up into pulp, they move outwardly from the center of the impellerand through the perforations in the screen for discharge into theconduit 22. The pair of vanes 30 moves the slurry outwardly from thecenter of the impeller toward the screen 18, and the vanes 32 move theslurry in the opposite direction. This results in a pulsing wave ofmaterial traveling circumferentially about the screen 18, i.e., pressureand suction alternate across the holes in the screen, which etfectivelykeeps incompletely pulped solids from plugging the holes in the screen.The pumping effort outwardly is induced in part simply by rotation ofthe impeller plate 28 (without the aid of the teeth or vanes), and thiseifort is increased by outwardly pumping vanes 30. The eifect of thevanes is a function of their size and velocity, which is in turn afunction of the radial distance from the center and also of therotational speed of the impeller. An approximate balance must beestablished between pumping effort outwardly (induced by plate 28 andvanes 30) and pumping effort inwardly (induced by vanes 32), otherwiseplugging of the screen will occur.

When strips of unpulped or incompletely pulped solid materials, such asplastics, rags or paper, are caught on the teeth of the impeller, eachtrails the tooth upon which it is caught and tends to cover the nextfollowing tooth.

Thus the surface of the impeller soon is covered with solid materialsand the eciency of the apparatus is reduced. Therefore, it is importantto note that the leading edges of the pulsing vanes and of the cuttingteeth all incline upwardly and rearwardly so that any solid materialstending to lodge thereon are readily shed.

What is claimed is:

1. In apparatus of the character described, the combination comprising atank, a closure for an opening in the bottom of said tank including anannular screen extending about said opening and through which pulpedsolids must pass in order to be discharged from said tank, and animpeller including a plate mounted for rotation within said screen, aplurality of circumferentially spaced upstanding impeller vanes on theupper surface of said plate certain of which are oriented for directingthe pulped solids outwardly from said plate toward said screen andothers of which are oriented for directing the pulped solids inwardly ofsaid plate away from said screen, and means for rotating said impellerwhereby to induce waves of pulped solids moving circumferentially ofsaid tank to pulsate with respect to the perforations in said screenthereby to dislodge solid particles tending to dwell there- 2. Thecombination according to claim 1 wherein the vanes are elongatedelements alternate ones of which are disposed with their leading endsfarther away from the outer edge of said plate than their trailing ends,and intervening ones of which are disposed with their leading endscloser to the outer edge of said plate than their trailing ends.

3. The combination according to claim 2 wherein each vane is atriangular plate element having two long edges and a comparatively shortedge, one of the longer edges of the vane is seated upon the impellerplate, and the vane is disposed with the other of its longer edgesleading.

4. The combination according to claim 2 wherein each vane is atriangular plate element, one edge of the vane is seated upon theimpeller plate, and the leading edge of the vane is inclined upwardlyand rearwardly.

5. The combination according to claim 1 wherein a plurality of teeth aredistributed over the upper surface of the impeller plate, said teethbeing operative for reducing solids to a pulp, and each tooth consistingof an element having a leading portion inclined upwardly and rearwardly.

6. The combination according to claim S wherein the vanes are elongatedelements alternate ones of which are disposed with their leading endsfarther away from the outer edge of said plate than their trailing ends,and intervening ones of which are disposed with their leading endscloser to the outer edge of said plate than their trailing ends.

7. The combination according to claim 6 wherein each vane is atriangular plate element, one edge of the vane is seated upon theimpeller plate, and the leading edge of the vane is inclined `upwardlyand rearwardly.

8. The combination according to claim -wherein the opposite sides of thetooth are coincident respectively with planes intersecting on a linecoincident with a leading edge of the tooth and disposed substantiallyat right angles to each other.

9. The combination according to claim 8 wherein the leading edge of thetooth is disposed at an angle of approximately thirty-five degrees fromthe vertical.

10. The combination according to claim 8 wherein the leading edge of thetooth is disposed at an angle of approximately thirty-five degrees fromthe vertical, andA the back of the tooth is coincident with a planedisposed substantially at a right angle to saidleading edge of thetooth.

11. In a pulping tank having a rotatable impeller disposed at the bottomthereof, the impeller comprising a plate mounted for rotation about itscentral axis, and a plurality of teeth distributed over the uppersurface of said plate and operative for reducing solids to a pulp uponrotation of the impeller, each tooth consisting of an element having aleading portion inclined upwardly and rearwardly wherein the oppositesides of the tooth are coincident respectively with planes intersectingon a line coincident with a leading edge of the tooth and disposedsubstantially at right angles to each other.

12. The combination according to claim 11 wherein the leading edge ofthe tooth is disposed at an angle of approximately thirty-five degreesfrom the vertical.

13. The combination according to claim 11 wherein the leading edge ofthe tooth is disposed at an angle of approximately thirty-five degreesfrom the vertical, and

the back of the tooth is coincident with a plane disposed substantiallyat a right angle to said leading edge of the tooth.

14. In a pulping tank having a rotatable impeller disposed at the bottomthereof, the impeller comprising a plate mounted for rotation about itscentral axis, and a plurality of teeth distributed over the -uppersurface of said plate and operative for reducing solids to a pulp uponrotation of the impeller, each tooth consisting of an element having aleading edge portion inclined upwardly and rearwardly, and each saidtooth along opposite sides of said leading edge having nonparallelapex-defining opposed surface portions connecting said leading edge andimpeller upper surface for the length of said leading edge.

15. The combination according to claim 14, wherein all saidplate-mounted teeth are upwardly disposed.

16. An apparatus of the character described, the combination comprisinga tank, a closure for an opening in the bottom of said tank including anannular screen extending about said opening and disposed for deningmeans for facilitating the direct passage of impelled pulped solidstherethrough, through which pulped solids must pass in order to bedischarged from said tank, and an impeller including a plate mounted forrotation within said screen, a plurality of circumferentially spacedupstanding impeller vanes on the upper surface of said plate certain oflwhich are oriented for directing the pulped solids outwardly from saidplate toward said screen and others of which are oriented for directingthe pulped solids inwardly of said plate away from said screen, andmeans for rotating said impeller whereby to induce waves of pulpedsolids moving circumferentially of said tank to pulsate with respect tothe perforations in said screen thereby to dislodge solid particlestending to dwell thereon.

References Cited UNITED STATES PATENTS 2,265,936 12/1941 Cowles 259-962,272,573 2/ 1942 Messmore 259-96 2,641,971 6/1953 Ellis 241-742,852,200 9/1958 Holzer 241-46 2,956,753 10/1960 Williamson 241-98 X3,009,656 11/1961 Martindale 241-46 3,028,634 4/1962 Coghill 241-296 XFRANK T. YOST, Primary Examiner U.S. Cl. X.R.

24l-l9l, 195, 296, 259-96

